The present invention relates generally to the field of tools. The present invention relates specifically to a tool, such as a level or a spirit level, including a removable and/or interchangeable outer protective cover or sleeve. Levels, such as spirit levels, are used to determine the levelness of a structure, surface or workpiece. In use, the level is placed on or in contact with a surface to be measured, and the user views the location of a bubble within a vial relative to markings that indicate the levelness of the structure, surface or workpiece.